Brake



Nov. 26, 1940. L. E. LA BRIE 222,848

2 BRAKE Filed New 22, 1937 s sheets-sheet 2 INVNTOR Nov. 26, 1940. L. E. LA BRIE 2,222,848

ISRAKE Filed Nov. 22, 1 957 3 Sheets-Sheet 3 L244 V48 `260 L262 y V l INVENTOR Y l5, I I BQOGEQ E H5215- ATTORNEY Patented Nov. 26,

M-TED STATES PATENT OFFICE BRAKE v i 'mager La. Brie, Detroit,`mch., signor to Bendix Aviation Corporation, South Bend, Ind.,

a corporation of DelawareA Application November 22, v1932, Serial No. 175,785

4 claims. (ci. esc-54.6)

This invention relates to brakes and more particularly to hydraulic brake systems.

An object of the inventionis to provide a .hy-

' draulic system in which'positive pressure is main- Atained on the return stroke of the piston to preventv the sucking of air into the system.

Another object is to provide ahydraulic brake system with amaster cylinder which acts as 'a pump to ll the systemrwith liquid.

Another object isC to provide a hydraulic brake system which is amply compensated for changes in temperature and leakage. L Further objects and desirable particular constructions will be more apparent upon reference to 'the following detailed description of several embodiments illustrated in the accompanying drawings, in which:

Figure 1 is a diagrammatic view showing a brake system constructed according to my invention; y

Figure 2 is a vertical longitudinal section through the master cylinder and part of the reservoir of my novel brake system;

Figure 3 is a. view similar to Figure l of a. modied form of my invention; Y

Figure 4 is a view similar to Figure 2 of th modification of Figure 3; and

Y Figures 5 and 6 are views corresponding to Figures 1 and 2 of stillanother modification of -my 80 invention. Y

J Referring particularly to Figures 1 and 2 of the drawings thereis disclosed a,brake system including a master cylinder i2, a supply reservoir eylinderis connected with thet reservoir 'through a conduit 24 and 22 througha conduit 26.

The master cylinder I2 comprises a main casting 28 formed with a main bore 30 and with intersecting bores 32, 34, and 36. The bore 3g extends through the rearward endof the casting 28 but does not extend through the forward end 38 thereof. The rearward end of the bore is threaded internally as at-40 and is provided with an annular plug 42 which normally serves to .seal the rearward end of the cylinder. The plug42 has associated therewith packings 44, 46, and 48 which aid in sealing the rear end of the cylinder. 50 Sliding through the opening in thev plug 42 and contacting with the packings 46 and A48 is a pis- 4 with the wheel cylinder 'tori rod 50 which s'erves to transmit force from the pedal to the piston. l

Surroundingth pistonrod and contacting with a shoulder 96 formed thereon is th'e master a uid motor or wheel cylinder 22. The master ,'niilar cup packing 62.

-piston which' has associated therewith an an- The piston rod extends forwardly through an openingin the forward end 38 oLthe cylinder and is lsealedl against leakage by packings -52 and54. IA spring interposed l between the packings 54' and 62 serves to main--v tain them in contact with the forward end 3 8 of the cylinderand the piston 60 respectively and also serves to return the piston 60 to its normalposition as shown. A split washer 54 secured on 10 the projecting end of the piston rod 50 serves to l. determine the .release position of the piston and stggi rod by engaging the front end or the castg Force applied to the pedal (not shown) acts 16 through a tting 58 universally secured to the piston connection 58 to force theV piston 60 forward desirable that 'there shall be a free interchange 25 of liquid between the reservoir and the master Icylinder when the master cylinder piston is in its normal position (as shown) and thatsubstantially free passage of liquid may be allowed from the reservoir to the master cylinder at all times, 30 but it is also desirable that `relatively high pressures shall be maintained upon .the liquid during operation of the brake without allowing any portion thereof to return to the reservoir during operation of the brake. Moreover, -it is desirable $6 that relatively high pressures should be developed upon the liquid rearwardly lof the piston while the brake is being releasedsand while the piston is moving rearwardly. Therefore, I have provided a double acting checkl valve 68 which is 4o positioned to Ccontrol the ow of liquid 'through the bore 32 and which is by-pas'sed by the bore 34. 'I'he valve 68 comprises a plug 'I0 connected atlits outer end tothe conduit 24 and threaded into an enlarged -portion of the bore 82. The 45 plug is formed with a central concentric stepped bore 12 and is provided with a sleeve 'I4 -posif tioned therein adjacent the inner end. A washf: er 16 is urged by a spring 18 to contact with the outer end of the sleeve 14. A ball check is 50 urged by relatively weak spring 82 to contact with the washer-16. A transverseborc intersects the bore 12 and cornects with an annulargroove 86 which registers with thexbore`34. 'f 'The piston 80 is formedwith an annular groovef 6I and is provided with a. series of ports such as B3 leading from the groove 8| to the rear face of the paclnng cupA 62.

The washer 16 in addition tp its central open- `ing 11 is provided with a plurality of small openings 88 through which liquid may pass outward from'the master cylinder when the washer 16 is lifted from its seat by pressure exceeding the strength of the spring 18.

Pressure exerted upon the pedal operates through the fitting 58 to move the piston 60 forward. This forces the liquid in the master cylinder in front of the piston 60 through the iitting 86 and the conduit 2E to the wheel cylinder 22 to spread the shoes I8 and 20 to contact with the drum I6 and thus causesthe shoes to anchor upon the anchor 2|. When the pedal is released the spring 84 moves the piston 60 rear' wardly until the pressure reaches the value of the spring 18. Should there be a tendency to develop a vacuum in the master cylinder in advance of the piston 60, the liquid rearwardly of the piston will be forced by the pressure through the ports 63 past the annular packing cup 62 to eliminate'the vacuum. As soon as the piston 6U has reached the inactive position shown (which is determined by the engagement of the washer 54 with the front of the cylinder substantially free interchange of liquid between the reservoir 4 and the front portion of the master, cylinder 1s allowed by reason of the bore 34, the groove 86, the bores 84, the bore 12, and the conduit 2l.

The modification shown in Figures 3 and 4 is substantially the same in construction and operation and I have designated corresponding parts therein by the same reference numeral. In this modification the piston |60 is solid and 1s somewhat loosely tted to permit uid to flow forward (to the right) past it, the packing |62 40 acting as a check valve to prevent return ow.

'I'he check valve arrangement' |68 is not built into the casting |28 but is provided separately in the conduit |24, and a second conduit |24' is provided to conduct uid from the reservoir to the compensating port |34.

In the modication of Figures 5 and 6, I have used the same reference numerals to designate parts corresponding to parts of Figures 1 and 2 plus 200.

In this modification the check valve arrangement 268 consists of two separate oppositelyacting check valves 218 and .280.postioned in the bottom of the reservoir 2|4, and communicating with the conduit 224.

vA branch conduit 224' extends from the conduit 224 to the compensating port 234 so that in this modification I do not have atmospheric compensation, but, instead, eircess fuel `is discharged at-the pressure'of the spring 218 thus maintaining pressure in the system at all times.

The piston 26D is hollow and is pierced fromv front to rear by ports 263, the port in the forward wall being rather large and centrally positioned. ...n

In this port is loosely fitted the stem of a valve 65, having a sealing member 61 seating on an annular rim 69 formed on the front face of the piston 260. This valve is held open by a light t spring 1| and closes when the piston is moved 70 forwardly because of the increase in pressure but opens to permit fluid to flow from the rear of the piston to the front thereof when the piston is released.

The operation of this modification should be` easily understood in connection wit'n the description of the preceding embodiments.

This application is a continuation in part oil a copending application Serial No. 661,613 led March 18, 1933 by myself jointly with Joseph R. Heidloif, and issued as Patent No. 2,140,751 on Dec. 20, 1938.

While three embodiments of my invention have been described in detail, it is not my intention to be limited to those embodiments, or otherwise than by the terms of the appended claims.

I claim:

l. -In a liquid pressure mechanism, a cylinder, a piston reciprocable therein, means forming a liquid containing chamber at the rear of the piston the volume of which varies with the piston movement, said piston being provided with means vpreventing liquid from passing the piston on 'its forward stroke .but permitting such passage on the return stroke, a reservoir, valve meanslfor admitting liquid to the chamber from the reservoir on the forward stroke of the piston, and valve means permitting liquid to iiow from the chamber to the reservoir when the piston during its return stroke applies a predetermined pressure to the liquid in the chamber. y

2. In a liquid pressure mechanism, a compression cylinder, a piston reciprocable therein for alternately creating superatmospheric pressure and subatmospheric pressure in said cylinder, means permitting flow of fluid past the piston in one direction only, a chamber forming a seal for preventing leakage of air past said piston during the return stroke thereof, a fluid reservoir, a single connection between said fluid reservoir and said seal, a second connection between said uid reservoir and that part of said cylinder in front of said piston, valve means for admitting liquid to the chamber from the reservoir on the forward stroke of the piston, and valve means permitting' liquid to ow from the chamber to the reservoir when the piston during its return stroke applies a predetermined pressure to the liquid in the chamber.`

3. In a liiuid pressure mechanism, a cylinder,`

a piston reciprocable therein, a reservoir, means forming a passage .between the reservoir and the cylinder, said passage being uncovered by the piston in its retracted position, a fluid containing chamber at the rear of the piston the volume of which varies with the piston movement, means forming a passage between thereservoir and the chamber, means permitting fluidto flow from said chamber past the piston on its return stroke, valve means for admitting liquid to the chamber from the reservoir on the forward stroke of the piston, and valve means permitting liquid to iiow from the chamber to the reservoir when the piston during its return stroke applies a predetermined pressure to the liquid in the chamber. i

4. In a liquid pressure mechanism, a cylinder, a piston reciprocable therein, means forming a liquid containing chamber at the rear of the piston the volume of which varies with the piston movement, said piston being provided with means preventing liquid from passing the piston on its forward stroke but permitting such passage on the return stroke, a reservoir, valve means be- LUDGER E. LA BRIE. 

